I think this is an informative writing. Here I gather some information about Radioactivity.
In the 1890s many scientists became caught up in the study of cathode rays and other kinds of rays. Some of these rays were associated with the newly discovered phenomenon called radioactivity, which is the spontaneous emission of radiation. Radiation is the term used to describe the emission and transmission of energy through space in the form of particles and/or waves. A radioactive substance decays, or breaks down, spc taneously. By the early twentieth century scientists had discovered several types of radioactive “rays.” Information gained by studying these rays and their effects on other materials contributed greatly to the growing understanding of the structure of the atom.
In 1895 Wilhelm RontgenJ noticed that when cathode rays struck glass and metals, new and very unusual rays were emitted. These rays were highly energetic and could penetrate matter. They also darkened covered photographic plates and could produce fluorescence in various substances. Since these rays could not be deflected by a magnet, they did not consist of charged particles as did cathode rays. Rontgen called them X rays. They were later identified as a type of high-energy radiation.
Not long after Rontgen’s discovery, Antoine Becquerel,§ a professor of physics in Paris, began to study fluorescent properties of substances. Purely by accident, he no-ticed that a certain compound containing uranium darkened photographic plates that were wrapped in thick papers or even in thin metal sheets, without the stimulation of cathode rays. The nature of the radiation that was doing this was not known, although, like X rays, it was highly energetic and did not consist of charged particles. One of Becquerel’s students, Marie Curie,j suggested the name 4′radioactivity” for this phenomenon. Any element, such as uranium, that spontaneously emits radiation is said to be radioactive. Marie Curie and her husband, Pierre, later studied and identified many radioactive elements.
Further investigation showed that three types of rays can be emitted by radioactive elements. These rays were studied by using an arrangement similar to that shown in Figure 2.4. It was found that two of the three types of rays could be deflected when they passed between two oppositely charged metal plates. Depending on the deflection, these two rays are called alpha (a) rays and beta (j8) rays. The third type of ray, which is unaffected by charged plates, is called a gamma (?) ray. a Rays or a particles were found to be particles with a positive charge of +2. They are therefore attracted by the negatively charged plate. The opposite holds true for /} rays or ft particles—they consist of negatively charged electrons, which are drawn to the positively charged plate. Because y rays do not consist of charged particles, their movement is unaffected by an external electric field. They are high-energy radiation.
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